In commercial operations where very large numbers of similar documents must be produced and mailed, a very small savings per document will translate into a large saving over the many documents. Examples of such documents are payroll checks, direct mail solicitations, 1099 forms, invoices, business statements, coupons, sales pieces, student grade reports, membership notices, and so forth. There are many other examples.
Traditional expenses for such operations include the cost of printing the documents, and labor for such tasks as folding, stuffing envelopes, and addressing.
In recent years, especially with the rapid growth of computer control techniques, equipment has been developed to produce self-mailers from single sheets. This process takes a single sheet and folds it in concert with an application of adhesive (or activation of existing areas of adhesive), perforates the edges for ease of opening, and seals the sheet into a unit known in the art as a self-mailer. The self-mailer becomes its own envelope, and no stuffing of envelopes is needed.
There are a number of different types of self-mailers known in the art and a number of different procedures for making them. For example, a type of adhesive that may later be activated with water may be applied to single sheets, which are then fed automatically through a laser printer, and then to a self-mailer machine that moistens the adhesive strips, folds the sheets, perforates the sheets appropriately for the particular form, and seals the unit together as a self-mailer. This kind of adhesive is the type used for flaps of most envelopes, and thus is familiar to most everyone.
The moistenable adhesive approach is used by manufacturers who judge it too difficult and troublesome to apply adhesive at the self-mailer machine; and if not done properly, applying glue at the self-mailer machine can be truly troublesome.
The pre-gluing approach, however, has its own drawbacks. For example, applying moistenable adhesive to the single sheets cannot normally be done in concert with printing, because the adhesive must be allowed to cure before coming in contact with the printing equipment or even other single sheets. Moreover, even cured, the moistenable adhesive is often not compatible with printing equipment, especially laser printers which operate by applying a high local temperature to the paper upon which printing is to be done. The high temperature often softens the adhesive and renders it tacky, creating jams and cleaning problems. Further, moistening the adhesive in the self-mailer machine can be just as troublesome as applying adhesive, because water can get onto regions where it isn't wanted and can also damage the equipment.
The approach of moistenable adhesive to avoid applying adhesive at the self-mailer machine is often, therefore, more expensive than the problems it is meant to avoid. The application of the moistenable adhesive is a separate operation with its own attendant costs, the problems the adhesive causes in printing equipment, particularly laser printing equipment, slows down the printing operation making it more expensive, and no balancing savings is realized at the self-mailer machine.
Still, until the present invention, the serious problems of applying adhesive directly at the self-mailer machine have never been adequately addressed. These problems include controlling glue "guns" to start and stop in concert with machine speed to put the adhesive just where it is wanted, applying the adhesive at rates allowing maximum operating speeds so the speed of operations is not limited by the adhesive application, avoiding plugging of applicators between runs, cleaning of the equipment, and loading new supplies of adhesive.
Another issue is the kind of glue to be applied. There are a number of different kinds of glue, including "hot melt" types, which solidify and adhere on cooling, and "cold" glue, which generally reacts with air to dry. Hot melt glue is notoriously difficult to apply at high speed, and also messy and problematic when it comes time to clean equipment.
Another difficulty with self-mailer machines is in the fact that single sheets used for the mailers and fed to the self-mailer machine are not always cut exactly square, and out of squareness can interfere with feeding of the sheets, which is done at rates of 20,000 per hour and higher. High speed is, of course, very desirable.
Yet another difficulty is in the periodic maintenance required for such machines, particularly those that feed adhesive at the self-mailer machine. The adhesive can be difficult to handle and messy, and can cure to stop up feeders. Moreover, adding new adhesive is a real problem with most machines.
Still another difficulty is that self mailers produced by a machine tend to open up before the adhesive is fully cured after the self-mailer leaves the machine that produces it. This problem has never been adequately addressed in the art.
Still another problem is that it is often desirable to perforate sheets and mailers in several different lines. It may be desirable, for example, to perforate a self-mailer along the short edges in "perf" lines that are in the direction that the mailer passes through the self-mailer machine. "Perf" lines of this sort are the familiar perforations at the "ends" of an envelope formed as a self-mailer. It may be desirable, however, to make one or more "perf" lines across the width of a mailer at right angles to the "perf" lines at the ends of the envelope. This operation generally requires either rotating the self-mailer ninety degrees in the self-mailer machine, or gathering the self-mailers as they exit the machine and sending them through another machine.
What is needed is a self-mailer machine with a sub-system for applying adhesive, preferably cold adhesive, in a manner that allows high operating speed while providing for adjustment to keep the adhesive where it is wanted. The adhesive system must allow for periodic stoppage to reload forms, change operations, and so forth, without danger of plugging adhesive applicators, and also must allow for reloading adhesive without extensive downtime for cleaning such as glue-pots and applicators. Applying adhesive directly at the self-mailer machine avoids all of the problems of application of adhesive prior to the self-mailer machine, and, properly done, provides for the fastest and least costly means of making self-mailers.
The machine also needs to have a means for insuring that self-mailers made on the machine stay folded and sealed until the glue sets up or cures to a sufficient extent to keep the self-mailer together. To add utility, the self-mailer machine needed also should have a means for turning self-mailers in process by about ninety degrees, and adding perforation lines at right angles to the original direction of travel through the self-mailer machine.